Heater for liquefied gas



March 21, 1950 $11 cLAlR 2,501,419

I HEATER FOR LIQUEFIED GAS Filed Dec. 10, 1945 BY? (4 ado n ATTO R N EYS Patented Mar. 21, 1950 HEATER FOR LIQUEFIED GAS Theodore A. St. Clair, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application December 10, 1945, Serial No. 634,050

Claims.

This invention relates to heaters. In one of its more specific aspects it relates to heater assemblies adapted to the heating of a liquefied gas in a storage tank to insure vaporization and a flow of gas under all conditions.

In northern and other areas of the United States, especially in the winter season, liquefied petroleum gases have been found to require some heating to insure vaporization and a fiow of gas under all weather conditions. Heating of the liquid fuel, such as butane or mixtures of butane and propane is frequently necessaryon account of the boiling point and vapor pressure considerations. Even propane, normally boiling at a very low temperature and having a relatively high vapor pressure under normal atmospheric conditions, requires some heating in many localities. Rapid vaporization during heavy load periods further increases the necessity for heating for maintenance of suitable working temperature and pressure.

One object of my invention is to provide heating means for use in tanks in liquefied petroleum gas service.

Another object of my invention is to provide heating units which are simple in construction and easy to install and to operate for service in liquefied petroleum gas service.

still another object of my invention is to provide heating units which are safe to use in connection with liquefied petroleum gas installations.

Still other objects and advantages will be apparent to those skilled in the art from a careful study of the following disclosure, which taken in conjunction with the attached drawing, forms a part of this specification.

In the drawing,

Figure 1 illustrates one application of my heater assembly.

Figure 2 is a longitudinal section, in part, showing the construction of one form of my heater.

Figure 3 is a cross sectional view of the radiator portion of the form of heater shown in Figure 2 and taken on the line 3-3.

Figure 4 is a longitudinal section showing the construction of another form of heater.

Referring to the drawing, and particularly to Figure 2, reference numeral l identifies a tank section through which a heater portion 8 of my heater assembly is inserted. This heater or radiator 8 is made of a good heat conducting metal, for example such as copper or aluminum. This member is constructed and installed in such a manner that its outer end is heated by a flame and the heat is conducted by the metal to the radiator portion which is within the tank and in direct contact with the liquid to be heated. Fins as shown in Figure 3 increase the heat radiating surface. In Figure 2, a burner B supplied with a fuel gas from some source furnishes a fiame for heating the exterior portion of the conductive metal. Two fire checks, 9 and l, which may be preferably of the Davy safety lamp type are inserted at positions shown to prevent explosions and fires when such a heating apparatus is located in an area which may contain a combustible gas. The fire checks may be made of such heat conducting material as copper or other substantially noncorrosive metal. These members may be of a wire gauze or screen form or layers of corrugated or honeycombed sections of thin copper or other suitable sheeting. The sections of heat conductor material disperse heat from a flame so rapidly that a gas on the other side of said means will not be ignited by such flame. Such members are more or less of stand ard design and may be purchased in the market ready-made. The fire check 9 protects the draft inlet opening while the check I0 protects the burned gas outlet opening.

An assembly as illustrated in this Figure 2, for many installations, may be of such size as to fit into standard 2 inch threaded openings such as are used in oil drums, tanks and other such equipment.

The exact length of the radiator member 8 is not critical and may be varied to suit the particular heating problem at hand. Its length will of course be dependent upon the heat conductivity properties of the particular metal used. A radiator of a metal having better heat conducting properties may be shorter than one made from a poorer heat conducting metal.

Figure 4 illustrates a heating element of a somewhat different type than that shown in Figures 2 and 3, but is adapted to the same use. This type of heater may be termed a convection heater since the heat is carried by moving gases. A burner 6 furnishes hot gases which flow upward within an inner tube l2, then pass from the open end thereof downward through an annular space between this inner tube l2 and an outer tube 13. Heat from this downward flowing gas passes through the walls of the outer tube l 3 which is in direct contact with the liquid to be heated. During the downward movement of the hot gases in this annular space they are rapidly cooled, and by the time the exit point is reached the flue gas is relatively cool. This radiator member 8 should preferably be of such length and made of a good heat conducting metal, like copper, that the available burner heat is fully devoted to serving the intended purpose. The flow of this burned gas is of course upwardin the inner tube I2 due to the heating effect from the flame and passes downward through the annular space from the added efiect of becoming cooled. The net result is a slow but definite flow of gases in the directions indicated by the arrows in Figure 4.

Fire checks 9 and III are installed in positions similar to those mentioned in connection with Figure 2. These are likewise made in a similar manner and of the same good heat conducting metal.

This heater element also may be of such a diameter for many installations that it can be threaded as shown and screwed into a standard 2 inch threaded tank opening.

Either embodiment of heater 8 as illustrated in Figures 2 and 4 may be screwed into position as shown in the lower portion of a tank I, of Figure 1. The particular heater shown in Figure 1 is the rad-iational heater of Figure 2. The tank i has a vapor or gas outlet line 2 which leads ultimately to points of gas consumption. In the line 2 is a pressure reducing regulator 3 which is adapted to reduce the pressure of the gas from that within the tank to that necessary for gas appliance operation. This pressure reducing regulator 3 is standard equipment obtainable from dealers in such items. From this regulator 3 the fuel carrying line passes on and is wrapped around the barrel or body portion of the heater assembly in such a manner that any liquid in line 4 will be vaporized or gas in this line will be warmed sufliciently that it will not condense while in transit to points of consumption or to maintain it as a gas until the line extends into the ground and is not exposed to temperatures such as might cause fuel condensation to liquid.

A valve 1, called herein a minimum flame control valve, is merely a valve adapted to per-'- mit a continuous but small flow of gaseous fuel from line 4 to a burner line H. Such a valve, which may be a hand-operated needle valve, is necessary to insure at all times and under all operating conditions at least some flow of gas to the burner 5.

Controller II in the burner fuel line H is intended to be pressure actuated and adapted to control the flow of gas to the burner 6 according to the pressure of the liquefied petroleum gas in the storage tank 1. Obviously as pressure in the storage tank increases over a certain maximum value, this controller operates to throttle down the flow of fuel gas to the burner. Then as heat from burner 6 decreases, the contents of the tank cool and the pressure therein drops. Some pressure reduction and cooling of course occurs by withdrawal of gas through the line to the appliances. When the pressure within the tank drops to a certain minimum value, this con troller H operates to permit increased flow of fuel gas from a branch line i to the burner fuel line It, thereby increasing the burner flame and accordingly the heat to the tank contents. When the controller I I operates to close ofi the flow of fuel from the branch line i5 to the burner line 14, there is as mentioned hereinbefore some gas flow through the minimum flow control valve 1. In this manner, then the burner flame does not become extinguished even at times when the controller valve ll shuts off fuel flow completely. Controller I I may be a valve similar to those disclosed in the McAlear Manufacturing Co. catalog No. 44, pages 44 and 45, or in Davis Regulator C0. Bulletin No. G2, page 3, although other types of valves may also be used.

To light the burners of the heating units illustrated in Figures 2 and 4, it is merely necessary to remove the fire check in shown in Figure 2 and the the check 9 shown in Figure 4 for insertion of a lighted match. The fire checks may then be replaced.

The herein described heater units are compact and simple ln design and construction, and in addition are easy to install.

Flame impingement in close association with the high heat conductive metal parts assists in maintaining a rather high temperature differential from outside to inside the tank so as to effect a relatively rapid heat transfer.

The tire check members reduce fire or explosion hazards so that these heaters may be used under all conditions.

Any type of burner tip 8 may be used providing, of course, it be adapted to operate satisfactorily for the purpose as herein described.

Materials of construction may be selected from among those commercially available, and need not be of "special type. The heater members 8 should, however, be resistant to any corrosion from contact with the flames and from contact with the material being heated.

It will be obvious to those skilled in the art that many modifications and alterations of my heaters may be made and yet remain within the intended spirit and scope of my broad invention.

Having described my invention, I claim:

1. A heater for vaporizing liquefied petroleum gas comprising a burner means; safety means for admitting air for supporting combustion; safety means for removing flue gas resulting from said combustion; and a heat conducting means adapted to transfer heat from said burner to said liquefied petroleum gas to be vaporized, said latter means comprising two concentrically positioned tubular members having a common longltudinal axis and substantially vertically disposed when in operational position, said tubes forming an annular space therebetween, said inner tube having its upper end open and the outer tube having its upper end closed, said burner means being positioned within and at a point near the bottom of said inner tubular member, the bottom of said inner tubular member having therein said safety means for admitting air, said outer tube having an opening positioned at a point above the bottom of said inner tube means, and said outer tube opening having therein said safety means for removing flue gas, the outer tube member at its bottom being in gas tight connection with said inner tube member at a point intermediate said two fire check means.

2. A system for vaporizing liquefied gas which comprises a confined chamber; a heater assembly, asubstantial portion of which protrudes into the lower portion of said chamber; a vapor outlet in the upper portion of said chamber; a pressure regulator; a first conduit extending between said vapor outlet and said pressure regulator; a second conduit extending between said pressure regulator and said heater assembly and intermediate its ends being in indirect heat exchange relatlon with said heater assembly by a circuitous route about said heater assembly; flow control means in said second conduit downstream from said heat exchange; by-pass conduit means extending between said second conduit, upstream of said flow control means; and said heater assembly; a valve in said by-pass conduit means limiting flow therethrough; a third conduit extending between said first conduit and said flow control means; and a fourth conduit communieating between said second conduit, upstream from said flow control means, and a gas distribution system.

3. A system for vaporizing liquefied gas which comprises a confined chamber; a heater assembly, a substantial portion of which protrudes into the lower portion of said chamber, which assembly comprises a heat conductor means; a burner means positioned so as to be in operational contact with said conductor, and a barrel enclosing a space about said burner and a portion of said conductor means, said barrel having an air inlet and a flue gas outlet and fire checks positioned in said inlet and outlet; a vapor outlet in the upper portion of said chamber; a pressure regulator; a first conduit extending between said vapor outlet and said pressure regulator; a second conduit extending between said pressure regulator and said heater assembly and intermediate its ends being in indirect heat exchange relation by a circuitous route about said heater assembly; flow control means in said second conduit downstream from said heat exchange; by-

pass conduit means extending between said second conduit, upstream of said flow control means; and said heater assembly, a valve in said by-pass conduit means limiting flow therethrough; a third conduit extending between said first conduit and said flow control means; and a fourth conduit extending between said second conduit, upstream from said flow control means, and a gas distribution system.

4. The system of claim 3 wherein said heat conductor means is a solid, metallic heat conductor having a high conductivity for heat.

5. The system of claim 3 wherein said heat conductor means comprises two tubular members, one disposed concentrically within the other, the longitudinal axis of which coincide and are substantially vertically disposed when in operational position, the upper end of the inner tubular member being open and the upper end of the outer tubular member being closed, and said barrel is a continuation of said heat conductor means.

THEODORE A. ST. CLAIR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 213,157 Alvord Mar. 11, 1879 1,234,049 Lovell July 17, 1917 1,561,898 Antisell Nov. 17, 1925 1,816,177 Corbus July 28, 1931 1,980,424 Morgan Nov. 13, 1934 2,084,297 Martin June 15, 1937 FOREIGN PATENTS Number Country Date 502,112 Great Britain Mar. 13. 1939 

